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 * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt;

import java.awt.peer.CheckboxMenuItemPeer;
import java.awt.event.*;
import java.util.EventListener;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;
import sun.awt.AWTAccessor;


/**
 * This class represents a check box that can be included in a menu. Selecting the check box in the
 * menu changes its state from "on" to "off" or from "off" to "on." <p> The following picture
 * depicts a menu which contains an instance of <code>CheckBoxMenuItem</code>: <p> <img
 * src="doc-files/MenuBar-1.gif" alt="Menu labeled Examples, containing items Basic, Simple, Check,
 * and More Examples. The Check item is a CheckBoxMenuItem instance, in the off state."
 * style="float:center; margin: 7px 10px;"> <p> The item labeled <code>Check</code> shows a check
 * box menu item in its "off" state. <p> When a check box menu item is selected, AWT sends an item
 * event to the item. Since the event is an instance of <code>ItemEvent</code>, the
 * <code>processEvent</code> method examines the event and passes it along to
 * <code>processItemEvent</code>. The latter method redirects the event to any
 * <code>ItemListener</code> objects that have registered an interest in item events generated by
 * this menu item.
 *
 * @author Sami Shaio
 * @see java.awt.event.ItemEvent
 * @see java.awt.event.ItemListener
 * @since JDK1.0
 */
public class CheckboxMenuItem extends MenuItem implements ItemSelectable, Accessible {

  static {
        /* ensure that the necessary native libraries are loaded */
    Toolkit.loadLibraries();
    if (!GraphicsEnvironment.isHeadless()) {
      initIDs();
    }

    AWTAccessor.setCheckboxMenuItemAccessor(
        new AWTAccessor.CheckboxMenuItemAccessor() {
          public boolean getState(CheckboxMenuItem cmi) {
            return cmi.state;
          }
        });
  }

  /**
   * The state of a checkbox menu item
   *
   * @serial
   * @see #getState()
   * @see #setState(boolean)
   */
  boolean state = false;

  transient ItemListener itemListener;

  private static final String base = "chkmenuitem";
  private static int nameCounter = 0;

  /*
   * JDK 1.1 serialVersionUID
   */
  private static final long serialVersionUID = 6190621106981774043L;

  /**
   * Create a check box menu item with an empty label.
   * The item's state is initially set to "off."
   *
   * @throws HeadlessException if GraphicsEnvironment.isHeadless() returns true
   * @see java.awt.GraphicsEnvironment#isHeadless
   * @since JDK1.1
   */
  public CheckboxMenuItem() throws HeadlessException {
    this("", false);
  }

  /**
   * Create a check box menu item with the specified label.
   * The item's state is initially set to "off."
   *
   * @param label a string label for the check box menu item, or <code>null</code> for an unlabeled
   * menu item.
   * @throws HeadlessException if GraphicsEnvironment.isHeadless() returns true
   * @see java.awt.GraphicsEnvironment#isHeadless
   */
  public CheckboxMenuItem(String label) throws HeadlessException {
    this(label, false);
  }

  /**
   * Create a check box menu item with the specified label and state.
   *
   * @param label a string label for the check box menu item, or <code>null</code> for an unlabeled
   * menu item.
   * @param state the initial state of the menu item, where <code>true</code> indicates "on" and
   * <code>false</code> indicates "off."
   * @throws HeadlessException if GraphicsEnvironment.isHeadless() returns true
   * @see java.awt.GraphicsEnvironment#isHeadless
   * @since JDK1.1
   */
  public CheckboxMenuItem(String label, boolean state)
      throws HeadlessException {
    super(label);
    this.state = state;
  }

  /**
   * Construct a name for this MenuComponent.  Called by getName() when
   * the name is null.
   */
  String constructComponentName() {
    synchronized (CheckboxMenuItem.class) {
      return base + nameCounter++;
    }
  }

  /**
   * Creates the peer of the checkbox item.  This peer allows us to
   * change the look of the checkbox item without changing its
   * functionality.
   * Most applications do not call this method directly.
   *
   * @see java.awt.Toolkit#createCheckboxMenuItem(java.awt.CheckboxMenuItem)
   * @see java.awt.Component#getToolkit()
   */
  public void addNotify() {
    synchronized (getTreeLock()) {
      if (peer == null) {
        peer = Toolkit.getDefaultToolkit().createCheckboxMenuItem(this);
      }
      super.addNotify();
    }
  }

  /**
   * Determines whether the state of this check box menu item
   * is "on" or "off."
   *
   * @return the state of this check box menu item, where <code>true</code> indicates "on" and
   * <code>false</code> indicates "off"
   * @see #setState
   */
  public boolean getState() {
    return state;
  }

  /**
   * Sets this check box menu item to the specified state.
   * The boolean value <code>true</code> indicates "on" while
   * <code>false</code> indicates "off."
   *
   * <p>Note that this method should be primarily used to
   * initialize the state of the check box menu item.
   * Programmatically setting the state of the check box
   * menu item will <i>not</i> trigger
   * an <code>ItemEvent</code>.  The only way to trigger an
   * <code>ItemEvent</code> is by user interaction.
   *
   * @param b <code>true</code> if the check box menu item is on, otherwise <code>false</code>
   * @see #getState
   */
  public synchronized void setState(boolean b) {
    state = b;
    CheckboxMenuItemPeer peer = (CheckboxMenuItemPeer) this.peer;
    if (peer != null) {
      peer.setState(b);
    }
  }

  /**
   * Returns the an array (length 1) containing the checkbox menu item
   * label or null if the checkbox is not selected.
   *
   * @see ItemSelectable
   */
  public synchronized Object[] getSelectedObjects() {
    if (state) {
      Object[] items = new Object[1];
      items[0] = label;
      return items;
    }
    return null;
  }

  /**
   * Adds the specified item listener to receive item events from
   * this check box menu item.  Item events are sent in response to user
   * actions, but not in response to calls to setState().
   * If l is null, no exception is thrown and no action is performed.
   * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
   * >AWT Threading Issues</a> for details on AWT's threading model.
   *
   * @param l the item listener
   * @see #removeItemListener
   * @see #getItemListeners
   * @see #setState
   * @see java.awt.event.ItemEvent
   * @see java.awt.event.ItemListener
   * @since JDK1.1
   */
  public synchronized void addItemListener(ItemListener l) {
    if (l == null) {
      return;
    }
    itemListener = AWTEventMulticaster.add(itemListener, l);
    newEventsOnly = true;
  }

  /**
   * Removes the specified item listener so that it no longer receives
   * item events from this check box menu item.
   * If l is null, no exception is thrown and no action is performed.
   * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
   * >AWT Threading Issues</a> for details on AWT's threading model.
   *
   * @param l the item listener
   * @see #addItemListener
   * @see #getItemListeners
   * @see java.awt.event.ItemEvent
   * @see java.awt.event.ItemListener
   * @since JDK1.1
   */
  public synchronized void removeItemListener(ItemListener l) {
    if (l == null) {
      return;
    }
    itemListener = AWTEventMulticaster.remove(itemListener, l);
  }

  /**
   * Returns an array of all the item listeners
   * registered on this checkbox menuitem.
   *
   * @return all of this checkbox menuitem's <code>ItemListener</code>s or an empty array if no item
   * listeners are currently registered
   * @see #addItemListener
   * @see #removeItemListener
   * @see java.awt.event.ItemEvent
   * @see java.awt.event.ItemListener
   * @since 1.4
   */
  public synchronized ItemListener[] getItemListeners() {
    return getListeners(ItemListener.class);
  }

  /**
   * Returns an array of all the objects currently registered
   * as <code><em>Foo</em>Listener</code>s
   * upon this <code>CheckboxMenuItem</code>.
   * <code><em>Foo</em>Listener</code>s are registered using the
   * <code>add<em>Foo</em>Listener</code> method.
   *
   * <p>
   * You can specify the <code>listenerType</code> argument
   * with a class literal, such as
   * <code><em>Foo</em>Listener.class</code>.
   * For example, you can query a
   * <code>CheckboxMenuItem</code> <code>c</code>
   * for its item listeners with the following code:
   *
   * <pre>ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class));</pre>
   *
   * If no such listeners exist, this method returns an empty array.
   *
   * @param listenerType the type of listeners requested; this parameter should specify an interface
   * that descends from <code>java.util.EventListener</code>
   * @return an array of all objects registered as <code><em>Foo</em>Listener</code>s on this
   * checkbox menuitem, or an empty array if no such listeners have been added
   * @throws ClassCastException if <code>listenerType</code> doesn't specify a class or interface
   * that implements <code>java.util.EventListener</code>
   * @see #getItemListeners
   * @since 1.3
   */
  public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
    EventListener l = null;
    if (listenerType == ItemListener.class) {
      l = itemListener;
    } else {
      return super.getListeners(listenerType);
    }
    return AWTEventMulticaster.getListeners(l, listenerType);
  }

  // REMIND: remove when filtering is done at lower level
  boolean eventEnabled(AWTEvent e) {
    if (e.id == ItemEvent.ITEM_STATE_CHANGED) {
      if ((eventMask & AWTEvent.ITEM_EVENT_MASK) != 0 ||
          itemListener != null) {
        return true;
      }
      return false;
    }
    return super.eventEnabled(e);
  }

  /**
   * Processes events on this check box menu item.
   * If the event is an instance of <code>ItemEvent</code>,
   * this method invokes the <code>processItemEvent</code> method.
   * If the event is not an item event,
   * it invokes <code>processEvent</code> on the superclass.
   * <p>
   * Check box menu items currently support only item events.
   * <p>Note that if the event parameter is <code>null</code>
   * the behavior is unspecified and may result in an
   * exception.
   *
   * @param e the event
   * @see java.awt.event.ItemEvent
   * @see #processItemEvent
   * @since JDK1.1
   */
  protected void processEvent(AWTEvent e) {
    if (e instanceof ItemEvent) {
      processItemEvent((ItemEvent) e);
      return;
    }
    super.processEvent(e);
  }

  /**
   * Processes item events occurring on this check box menu item by
   * dispatching them to any registered <code>ItemListener</code> objects.
   * <p>
   * This method is not called unless item events are
   * enabled for this menu item. Item events are enabled
   * when one of the following occurs:
   * <ul>
   * <li>An <code>ItemListener</code> object is registered
   * via <code>addItemListener</code>.
   * <li>Item events are enabled via <code>enableEvents</code>.
   * </ul>
   * <p>Note that if the event parameter is <code>null</code>
   * the behavior is unspecified and may result in an
   * exception.
   *
   * @param e the item event
   * @see java.awt.event.ItemEvent
   * @see java.awt.event.ItemListener
   * @see #addItemListener
   * @see java.awt.MenuItem#enableEvents
   * @since JDK1.1
   */
  protected void processItemEvent(ItemEvent e) {
    ItemListener listener = itemListener;
    if (listener != null) {
      listener.itemStateChanged(e);
    }
  }

  /*
   * Post an ItemEvent and toggle state.
   */
  void doMenuEvent(long when, int modifiers) {
    setState(!state);
    Toolkit.getEventQueue().postEvent(
        new ItemEvent(this, ItemEvent.ITEM_STATE_CHANGED,
            getLabel(),
            state ? ItemEvent.SELECTED :
                ItemEvent.DESELECTED));
  }

  /**
   * Returns a string representing the state of this
   * <code>CheckBoxMenuItem</code>. This
   * method is intended to be used only for debugging purposes, and the
   * content and format of the returned string may vary between
   * implementations. The returned string may be empty but may not be
   * <code>null</code>.
   *
   * @return the parameter string of this check box menu item
   */
  public String paramString() {
    return super.paramString() + ",state=" + state;
  }

    /* Serialization support.
     */

  /*
   * Serial Data Version
   * @serial
   */
  private int checkboxMenuItemSerializedDataVersion = 1;

  /**
   * Writes default serializable fields to stream.  Writes
   * a list of serializable <code>ItemListeners</code>
   * as optional data.  The non-serializable
   * <code>ItemListeners</code> are detected and
   * no attempt is made to serialize them.
   *
   * @param s the <code>ObjectOutputStream</code> to write
   * @serialData <code>null</code> terminated sequence of 0 or more pairs; the pair consists of a
   * <code>String</code> and an <code>Object</code>; the <code>String</code> indicates the type of
   * object and is one of the following: <code>itemListenerK</code> indicating an
   * <code>ItemListener</code> object
   * @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
   * @see java.awt.Component#itemListenerK
   * @see #readObject(ObjectInputStream)
   */
  private void writeObject(ObjectOutputStream s)
      throws java.io.IOException {
    s.defaultWriteObject();

    AWTEventMulticaster.save(s, itemListenerK, itemListener);
    s.writeObject(null);
  }

  /*
   * Reads the <code>ObjectInputStream</code> and if it
   * isn't <code>null</code> adds a listener to receive
   * item events fired by the <code>Checkbox</code> menu item.
   * Unrecognized keys or values will be ignored.
   *
   * @param s the <code>ObjectInputStream</code> to read
   * @serial
   * @see removeActionListener()
   * @see addActionListener()
   * @see #writeObject
   */
  private void readObject(ObjectInputStream s)
      throws ClassNotFoundException, IOException {
    s.defaultReadObject();

    Object keyOrNull;
    while (null != (keyOrNull = s.readObject())) {
      String key = ((String) keyOrNull).intern();

      if (itemListenerK == key) {
        addItemListener((ItemListener) (s.readObject()));
      } else // skip value for unrecognized key
      {
        s.readObject();
      }
    }
  }

  /**
   * Initialize JNI field and method IDs
   */
  private static native void initIDs();

/////////////////
// Accessibility support
////////////////

  /**
   * Gets the AccessibleContext associated with this CheckboxMenuItem.
   * For checkbox menu items, the AccessibleContext takes the
   * form of an AccessibleAWTCheckboxMenuItem.
   * A new AccessibleAWTCheckboxMenuItem is created if necessary.
   *
   * @return an AccessibleAWTCheckboxMenuItem that serves as the AccessibleContext of this
   * CheckboxMenuItem
   * @since 1.3
   */
  public AccessibleContext getAccessibleContext() {
    if (accessibleContext == null) {
      accessibleContext = new AccessibleAWTCheckboxMenuItem();
    }
    return accessibleContext;
  }

  /**
   * Inner class of CheckboxMenuItem used to provide default support for
   * accessibility.  This class is not meant to be used directly by
   * application developers, but is instead meant only to be
   * subclassed by menu component developers.
   * <p>
   * This class implements accessibility support for the
   * <code>CheckboxMenuItem</code> class.  It provides an implementation
   * of the Java Accessibility API appropriate to checkbox menu item
   * user-interface elements.
   *
   * @since 1.3
   */
  protected class AccessibleAWTCheckboxMenuItem extends AccessibleAWTMenuItem
      implements AccessibleAction, AccessibleValue {

    /*
     * JDK 1.3 serialVersionUID
     */
    private static final long serialVersionUID = -1122642964303476L;

    /**
     * Get the AccessibleAction associated with this object.  In the
     * implementation of the Java Accessibility API for this class,
     * return this object, which is responsible for implementing the
     * AccessibleAction interface on behalf of itself.
     *
     * @return this object
     */
    public AccessibleAction getAccessibleAction() {
      return this;
    }

    /**
     * Get the AccessibleValue associated with this object.  In the
     * implementation of the Java Accessibility API for this class,
     * return this object, which is responsible for implementing the
     * AccessibleValue interface on behalf of itself.
     *
     * @return this object
     */
    public AccessibleValue getAccessibleValue() {
      return this;
    }

    /**
     * Returns the number of Actions available in this object.
     * If there is more than one, the first one is the "default"
     * action.
     *
     * @return the number of Actions in this object
     */
    public int getAccessibleActionCount() {
      return 0;  //  To be fully implemented in a future release
    }

    /**
     * Return a description of the specified action of the object.
     *
     * @param i zero-based index of the actions
     */
    public String getAccessibleActionDescription(int i) {
      return null;  //  To be fully implemented in a future release
    }

    /**
     * Perform the specified Action on the object
     *
     * @param i zero-based index of actions
     * @return true if the action was performed; otherwise false.
     */
    public boolean doAccessibleAction(int i) {
      return false;    //  To be fully implemented in a future release
    }

    /**
     * Get the value of this object as a Number.  If the value has not been
     * set, the return value will be null.
     *
     * @return value of the object
     * @see #setCurrentAccessibleValue
     */
    public Number getCurrentAccessibleValue() {
      return null;  //  To be fully implemented in a future release
    }

    /**
     * Set the value of this object as a Number.
     *
     * @return true if the value was set; otherwise false
     * @see #getCurrentAccessibleValue
     */
    public boolean setCurrentAccessibleValue(Number n) {
      return false;  //  To be fully implemented in a future release
    }

    /**
     * Get the minimum value of this object as a Number.
     *
     * @return Minimum value of the object; null if this object does not have a minimum value
     * @see #getMaximumAccessibleValue
     */
    public Number getMinimumAccessibleValue() {
      return null;  //  To be fully implemented in a future release
    }

    /**
     * Get the maximum value of this object as a Number.
     *
     * @return Maximum value of the object; null if this object does not have a maximum value
     * @see #getMinimumAccessibleValue
     */
    public Number getMaximumAccessibleValue() {
      return null;  //  To be fully implemented in a future release
    }

    /**
     * Get the role of this object.
     *
     * @return an instance of AccessibleRole describing the role of the object
     */
    public AccessibleRole getAccessibleRole() {
      return AccessibleRole.CHECK_BOX;
    }

  } // class AccessibleAWTMenuItem

}
